This project is concerned with the evaluation of variety of new diagnostic techniques which have yet to be applied in dentistry. Modalities studied include nuclear medicine (99mTe-MDP) assays, arthroscopy, fiber-optic systems making use of visible light (hemoglobin- specific spectrum analysis), and magnetic resonance (MR) imaging. Measurements of differential uptake of 99mTc-MDP in beagle dogs following induction of tiny alveolar lesions indicated the need for redesign of a commercially available miniature nuclear probe to increase spatial specificity. The addition of a properly designed collimator to the hand-held probe permitted reliable detection of the bone regeneration process in induced lesions int he alveolar bone and the condylar head in the temporomandibular joint (TMJ). In an effort to develop new diagnostic tools for TMJ evaluations, the healing of induced lesions in the condyle was also monitored by arthroscopy and subtraction radiography. Arthroscopy furnished detailed qualitative information on intracapsular soft tissues and the status of the cartilage surface which cannot be obtained by other methods, while subtraction radiography enable quantitation of the bone mass and shape changes of the condylar head. A prototype fiber-optic instrument was built to determine tooth vitality from the analysis of light scattered from the pulpal tissues. Display of the intensity ratio at two wavelengths within the 530 to 590 nm range demonstrated a cardiac pulse in dogs, which could be eliminated by root- tip transection. Similar pulsative signals could be derived from vital molars, bicuspids, nd incisors in human volunteers, demonstrating potential utility for endodontics. MR imaging was investigated to determine whether surgically induced stenosis of the salivary gland ducts can be detected reliably. The results indicate that T2-weighted images show significant differences between occluded and nonoccluded glands due to interacinar edema, and an excellent representation of the anatomy, possible obviating the need for contrast sialography.